The search for oil offshore has moved drilling and production activity further and further out to sea into deeper and deeper water. Activities now being carried on, such as the replacement of pipeline risers and the making of pipeline repairs, are at depths which exceed the safe level of operation for divers. In order to operate at such extensive depths, the utilization of a Remote Operated Vehicle (ROV) has become more and more common. An ROV is a propeller driven, fully remotely operable underwater vehicle utilizing TV cameras for eyes and having gripping arms and hydraulic power connections. The ROV can be completely controlled from a surface vessel and thus offers the advantage of avoiding the endangerment of human life. As the use of ROV submarines has increased, the need for adapting previously diver-type functions to diverless functions has emerged. One area in need of diverless operation is the repair and/or connection of oil and gas pipelines at such extensive depths.
A known technique for repairing a pipeline is to provide a repair spool which may be lowered down into alignment with pipeline ends which need to be re-connected together. Such a repair spool may include at each end or at one end a pivotal ball connector which allows the repair spool to be connected to each end of the pipeline to be repaired and compensates for some misalignment between the pipeline ends to be connected together by the repair spool. The Applicant here has recently filed U.S. patent application Ser. No. 608,384 entitled "Remote Ball Connector" which discloses a remote ball connector which may be mounted at one or both ends of a repair spool for the purpose of connecting such a repair spool to pipeline ends even though misalignment is present. The device disclosed in the patent application entitled Remote Ball Connector may be installed without the need of divers utilizing the ROV submarine.
Another part of such a repair spool is a pipe length compensator which is provided to connect together first and second repair spool pipe members to allow some relative axial movement between them so that the final length of the spool may be adjusted when in place. In order for such final repair spool length to be adjusted on site, it is necessary that a final gripping and sealing connection be made between the two pipe members of the repair spool on site in order to prevent leakage and to hold the repair spool portions in a rigid alignment. Such pipe length compensators are generally known in the art. For example, U.S. Pat. No. 4,138,147 discloses a pipe length compensator or variable length coupling device which is installed by a diver and includes flange bolt connections which actuate gripping and sealing elements in response to further connection of first and second housing members together. There have also been a number of attempts to utilize hydraulic power to connect together pipe portions. However, it is believed that the effectiveness of presently known, hydraulically operated pipe connector designs needs improvement and therefore this invention is directed to an improved pipe length compensator which utilizes hydraulic power and mechanical wedging action to effect the final connection.